Pneumatic tire tube



H n M S E PNEUMATIC TIRE TUBE Filed April 7, 1938 2 Sheets-Sheet l Invenior A itqrneys July 2, 1940; E, A, SMITH PNEUMATIC TIRE TUBE FiledApril 7, 1938 2 Sheets-Sheet 2 Inventor j z w 7 m a nk z gmmy E 1, Q /JM, 7 f M 3 w a f; m ww Attorneys Patented July 2, 1940 UNITED STATESPATENT orrics PNEUMATIC TIRE TUBE Edgar Alton Smith, New York, N. Y.Application April 7, 1938, Serial No. 200,773

3 Claims.

The present invention relates to new and useful improvements in tubesfor pneumatic tires and has for its primary object to provide, in amanner as hereinafter set forth, a tube having incorporated therein apump of a novel construction and arrangement for automaticallymaintaining the air in said tube at a predetermined pressure.

Other objects of the invention are to provide an automatically inflatedinner tube of the aforementioned character which will be comparativelysimple in construction, strong, durable, highly efficient and reliablein use, compact and which may be manufactured at low cost.

All of the foregoing and still further objects and advantages of theinvention will become apparent from a study of the followingspecification, taken in connection with the accompanying drawingswherein like characters of reference designate corresponding partsthroughout the several views, and wherein:

Figure 1 is a view in vertical section through a portion of an innertube embodying the present invention, the base portion of the pump beingshown in section with the rest of said pump in side elevation.

Figure 2 is a view in end elevation of the pump.

Figure 3 is a vertical sectional vi the pump.

Figure 4 is a view in horizontal section, taken substantially on theline 4-4 of Fig. 3.

I Referring now to the drawings in detail, it will be seen that thereference numeral l designates an inflatable inner tube mounted in aconventional casing 2. Formed integrally with the inner periphery of thetube I is a rubber base 3 having an air passage l therein. The base 3includes a tubulare stem 5 which is adapted to project through the rim 6on which the tire is mounted Mounted on the base 3 is a cylinder l ofsuitable material. The inner end of the cylinder 7 is closed, as at 8,and projecting therefrom is a neck 9 which is secured to an extension iton the base 3 for mounting said cylinder on said base. A pin H anchorsthe neck 9 to the extension Ill. The cylinder 1 is open at its outerend.

The reference numeral l2 designates a comparatively small outer cylinderwhich is adapted to be moved into the inner cylinder 7. The cylinder 5?is closed at its outer end, as at l3. The inner end of the cylinder I2is closed by a piston M which is fixed thereon and which is slidablyengaged in the cylinder I. The piston I l com- 55 prises a cup l5engaged with the walls of the gw through cylinder 1 in the usual manner.The piston i l further includes a disk 26 in the cup I 5, said diskbeing secured to the cylinder [2. The piston it still further includes acheck valve it through which air is forced from the inner portion of thecylinder I2 into the cylinder 1 by the piston l9. Any desired number ofthe check valves it may be provided in the piston M.

Also mounted in the extension ill on the base 3 and communicating withthe air passage l is a tube or conduit ii. The pin ll passes through theconduit H for anchoring same in the extension ill of the base 3. The airconduit ll constitutes an inlet pipe which extends through the cylinder7 and the piston It into the cylinder ill. The piston 14 is slidable onthe inlet pipe ii. A check valve 88 is provided in the inlet pipe ll toprevent the escape of the airfrom the outer portion of the cylinder l 2back through said inlet pipe ll. Mounted on the inlet pipe I? and up:-erable in the cylinder i2 is a piston l9 comprising a cup 20. The pistonit further includes a disk 21 in the cup 20.

Fixed on the closed end it of the cylinder i2 is a. nose 2! which isengageable with the outer periphery of the tube 2 in the manner shown toadvantage in Fig. 1 of the drawings. The base of the nose 2| comprises aflange 22 which projects beyond the periphery of the closed end it ofthe cylinder l2. A cupped flange 23 projects from the closed end 8 ofthe cylinder 1. The reference numeral 24 designates a coil spring whichencircles the cylinders "i and i2 and which has its ends engagedwith theflanges 22 and 2t.

Briefly, the operation of the device is substantially as follows:

The tire is first inflated to the desired pressure in the usual manner.This pressure is such that, acting on the piston It, the cylinder i2will be moved into the cylinder 7 against the tension of the coil spring24, thus moving the nose 2i out of contact with the tube l. With thecylinder l2 and the nose 2| in this position, the pump will not functionas the tire rolls over the highway. However, should the pressure in thetire drop to any considerable extent, the spring 2% will move thecylinder outwardly and contact the nose 2! with said tire. Then, whenthe tire flexes under the load as it contacts the highway the. cylinderIt with the piston Hi thereon will be forced into the cylinder 1 againstthe tension of the coil spring 24, the piston i9, of course, remainingstationary. Thus, air trapped in the cylinder 7 is forced past the cupl5 into the tube l and air trapped into the cylinder I2 is forced pastthe cup 20 into the chamber between said piston l4 and the piston l9.When the portion of the tire with which the nose ZI is engaged leavesthe highway the cylinder 12 is forced outwardly by the spring 24. Whenthis occurs, air from the atmosphere is drawn through the inlet pipe llinto the cylinder l2 and the air thus trapped between the pistons I4 andIS in the cylinder I2 is forced past the check valve I6 into thecylinder I. This operation is repeated until the pressure in the tirehas again been built up to the desired point when the piston M willagain be forced inwardly and held in this position, thus again movingthe nose 21 out of contact with the tire;

It is believed that the many advantages of an automatic tube inflatingmeans constructed in accordance with the present invention will bereadily understood and although a preferred embodiment of the device isas illustrated and described, it is to be understood that changes in thedetails of construction and in the combination and arrangement of partsmay be resorted to which will fall within the scope of the invention asclaimed.

What is claimed is:

1. A pneumatic tire including an inflatable tube, a cylinder mounted insaid tube on the inner periphery thereof, a piston operable in saidcylinder, a comparatively small cylinder mounted on the piston andprojecting outwardly therefrom, an air inlet pipe communicating with theatmosphere and extending through the first named cylinder into thesecond named cylinder, the piston being slidable on said inlet pipe, apiston fixed on the inlet pipe and operable in the second namedcylinder, a check valve in the inlet pipe for preventing the return flowof air to the atmosphere, the first named piston having a check valvecontrolled passage therein for admitting air to the first named cylinderfrom the second named cylinder, and a spring engaged with the secondnamed cylinder for yieldingly urging same outwardly for engagement withthe outer periphery of the tube for actuation thereby.

2. A pneumatic tire including an inflatable tube, a resilient baseintegral with the inner periphery of the tube, said base having an airpassage therein communicating with the atmosphere, a cylinder mounted onthe base in the tube, an air inlet pipe mounted in the air passage inthe base and extending longitudinally into the cylinder, a check valvein the inlet pipe, a piston fixed on said inlet pipe, a piston operablein the cylinder and slidably mounted on the inlet pipe, a comparativelysmall cylinder fixed on the second named piston and slidable on thefirst named piston, said second named piston having a check valvecontrolled opening therein for the passage of air from the second namedcylinder into the first named cylinder, the first and second namedpistons including cups engaged with the walls of the cylinders, andmeans for operatively connecting the second named cylinder to the outerperiphery of the tube for actuation thereby when said tube is flexed.

3. A pneumatic tire including an inflatable tube, a resilient baseintegral with the inner periphery of the tube, said base having an airpassage therein communicating with the atmosphere, a cylinder mounted onthe base in the tube, an air inlet pipe mounted in the air passage inthe base and extending longitudinally into the cylinder, a check valvein the inlet pipe, a piston fixed on said inlet pipe, a piston operablein the cylinder and slidably mounted on the inlet pipe, a comparativelysmall cylinder fixed on the second named piston and slidable on thefirst named piston, said second named piston having a check valvecontrolled opening therein for the passage of air from the second namedcylinder into the first named cylinder, the first and second namedpistons including cups engaged with the walls of the cylinders, andmeans for operatively connecting the second named cylinder to the outerperiphery of the tube for actuation thereby when said tube is flexed,said means including a nose member fixed on one end of the second namedcylinder, a flange projecting from the base portion of said nose member,a flange projecting from the first named cylinder, and a coil springencircling the cylinders and having its ends engaged with the flanges.

EDGAR ALTON SMITH.

